Systematic Implications of Fruit Wall Anatomy and Surface Sculpturing of <i>Microseris</i> (Asteraceae, Lactuceae) and Relatives

Abstract

The fruit wall anatomy and surface sculpturing of 17 taxa of Microseris and its two nearest relatives, the genera Uropappus and Stebbinsoseris, have been studied in order to assess their systematic significance. In total, 13 characters were described and scored. Four character states of the fruit wall anatomy were identical in the three genera. Some characters, for example, the cell layer and shape of the thick‐walled parenchyma formed near the exocarp, the shape of the fruit and costa, the cell size and shape of the intercosta, the continuity of the sclerenchyma between intercostae, and the coordinated and intrusive growth fiber cells, differed among species. The shape of the end wall of cells on the fruit surface has three states: tapering in subgenus Microseris and genus Stebbinsoseris, blunt in subgenus Scorzonella and genus Uropappus, and round in subgenus Moniermus. The ornamentation of the outer cell walls has five states: oblique papillae in subgenus Scorzonella, hairy trichomes in subgenus Moniermus, furfuraceous trichomes in subgenus Microseris and genus Stebbinsoseris, furfuraceous papillae in the genus Uropappus, and undeveloped in Microseris borealis. The epicuticular waxes have three states: weakly developed in subgenera Scorzonella and Moniermus, well developed in subgenus Microseris and genera Uropappus and Stebbinsoseris, and undeveloped in M. borealis. The current infrageneric classification of Microseris is well supported by these characters.